This invention relates to blends of polyvinyl chloride (PVC) and polystyrene. More particularly this invention relates to stable blends of PVC and polystyrene having incorporated therein a chlorinated styrene-butadiene block copolymer as a compatibilizing aid, and to a method for forming stable blends of PVC and polystyrene.
Polyvinyl chloride and polystyrene are rigid thermoplastic resins, each having wide commercial application. The resins differ markedly in solubility behavior, the high chlorine content making PVC more polar in character then polystyrene. Because the resins are not miscible and are otherwise not compatible, blends of the two polymers readily separate upon melt processing into discrete, discontinuous component domains. These domains do not adhere to one another well, which results in brittle, low strength moldings.
Methods for forming stable blends of PVC and polystyrene would be desirable. The successful incorporation of PVC into polystyrene compositions would be expected to impart reduced flammability to structural sheet and foam.